An animal model has been developed to evaluate sensory irritation of the upper respiratory tract due to exposure to airborne chemicals. A total of 11 industrial chemicals have been tested in this model and the results used to predict human reactions. Expansion of this model is proposed to include other categories of industrial chemicals as well as mixtures of them to firmly establish that Threshold Limit Values (TLVs) for industrial exposure can be predicted from this model when sensory irritation is the main criterion. The same model will be utilized to demonstrate possible pharmacological as well as immunologiacal sensitization with repeated exposure to these chemicals and also the possibility of tolerance development.